MIAMI — The magic of Patrick Mahomes proved too much for the San Francisco 49ers in Super Bowl LIV.

Facing a 20-10 deficit in the fourth quarter, Mahomes led a furious comeback with two touchdown passes to lead the Kansas City Chiefs to a 31-20 win, marking the team's first league championship since Super Bowl IV in 1970.

"We kept believing," Mahomes said. "That's what we did all postseason. I felt like when were down by 10, we weren't playing our best football.

"The guys really stepped up. They believed in me. I was making a lot of mistakes out there early. We found a way to win it in the end."

Mahomes shook off a slow start and two interceptions before reminding a world audience he was the league's MVP in 2018, and now the Super Bowl MVP. The third-year quarterback completed 26 of 41 passes for 286 yards and two touchdowns in the win, adding 29 yards rushing and a touchdown on nine carries.

At 24 years and 138 days old, Mahomes became the youngest quarterback to win the Super Bowl MVP.

Before the Chiefs' fourth-quarter comeback, the 49ers appeared to be in charge with a defense that held Mahomes and Co. in check. San Francisco harassed Mahomes through the first three quarters, totaling four sacks and eight quarterback hits.

The pressure forced Mahomes into just the second multi-interception game of his career, but defensive coordinator Robert Saleh's unit couldn't slow down Mahomes when it mattered.

"We have an ability as a team, not just an offense, as a team to figure out what the other team is doing and put our foot in the ground and say enough is enough," tight end Travis Kelce said. "You have a band of brothers that come together for one goal and are determined to go out with a sense of urgency to get things done."

Mahomes kept his poise midway through the fourth quarter. With 8:53 remaining in the game, the Chiefs' comeback began after Mahomes connected on a 44-yard pass to Tyreek Hill, which set up a 1-yard touchdown pass to Kelce.

After holding the 49ers to a three-and-out, the Chiefs scored when Mahomes found running back Damien Williams for a 5-yard touchdown pass that gave the Chiefs a 24-20 lead in a drive set up by wide receiver Sammy Watkins' 38-yard catch. Williams would put the icing on the cake with a 38-yard touchdown run down the left sideline with less than two minutes to go and finished the game with 104 yards rushing on 17 carries.

"Damien has put together three games now that have been powerful," Chiefs coach Andy Reid said. "When needed, he just bared down."

Williams, who tied a Super Bowl record with two touchdowns in a single quarter, gave credit to fullback Anthony Sherman for springing him loose on the game-sealing score.

"Honestly, it's funny because Sherm came in the game and was like, 'Follow me,'" Williams said. "That's exactly what I did; I followed him. The run was supposed to go inside, he went outside, so I went outside and I said, 'Screw it, I'm taking it to the house.' "

While Mahomes and Williams made it look easy late in the game, the first three quarters proved anything but that.

The two teams bobbed and weaved through the first two quarters, exchanging body blows as they appeared to measure each other in a physical contest en route to a 10-10 halftime tie.

"I took a couple of hits, I'll tell you that," Mahomes said. "I was just trying to fight."

Kansas City opened the game going three-and-out, which the 49ers capitalized on to take a 3-0 lead after kicker Robbie Gould capped off a 10-play, 62-yard drive with a 38-yard field goal.

Mahomes led the Chiefs to their first score on a 1-yard touchdown run on a drive highlighted by the Chiefs converting a fourth-and-1 at the 49ers' 5-yard line, which came on a direct snap to Williams, who took it to the 1-yard line. Two plays later, Mahomes punched it in.

The Chiefs signal-caller is the first quarterback to score a rushing touchdown in the Super Bowl since former 49ers quarterback Colin Kaepernick in Super Bowl XLVII.

Reid showed a gambling side to him, going for it on fourth-and-1 twice in the first half, converting both. The Chiefs join the 2017 Eagles, coached by Reid's former offensive coordinator Doug Pederson, as the only teams since 2000 with multiple fourth-down conversions in a Super Bowl game.

Hill finished the game with nine catches for 105 yards on 16 targets, while Watkins totaled five catches for 98 yards.

Defensively, the Chiefs held the 49ers scoreless in the fourth quarter, allowing the offense to score 21 straight points.

The Chiefs forced an interception off quarterback Jimmy Garoppolo and limited the 49ers to 59 total yards of offense in the final quarter. On the game, the Chiefs allowed the 49ers' vaunted three-heading rushing attack to total 141 yards and a touchdown on 22 carries, but the defense was able to make adjustments and slow down San Francisco's offense.

"I think our mindset is jut to finish the game," said safety Tyrann Mathieu, who finished the game with six tackles. "I think our d-coordinator Spags (Steve Spagnuolo), that's all he preaches — to never relax, to never get comfortable really unitl the game is over. I felt like that's what we did."

Cornerback Bashaud Breeland paced the Chiefs defense with seven tackles, an interception and a pass defensed, while defensive end Frank Clark totaled a sack.

Sunday's win provided Kansas City a long-awaited football championship. But to so many players, getting Reid his first Super Bowl championship in 21 years as a head coach proved special.

"I think that was our goal this whole week — to win this game for Coach Reid," Mathieu said. "He's been doing this a long time."

Linebacker Anthony Hitchens agreed.

"You should have seen the smile on his face with that Gatorade on him," Jones said. "It's good for him and a lot of other people. We all worked hard. We had a common goal. We came together."

The Chiefs overcame three straight double-digit deficits in the playoffs en route to becoming a Super Bowl-winning team. The accomplishment also has the Chiefs standing alone as the only team to win three postseason games in which they trailed by 10-plus points at some points.

Kansas City's comeback from a 10-point deficit matches the second-biggest comeback in Super Bowl history. After the 25-point comeback by the New England Patriots in Super Bowl LI, it is one of four 10-point comeback wins.

And for the Chiefs, the ability to battle through deficits helped pave the way to stand alone as NFL champions.

"It's special," Kelce said. "We showed it throughout the playoffs and showed it even more tonight."